linux-kernel - Re: [PATCH v2 3/6] mmc: core: refactor _mmc

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Message-ID: <0be29875-3254-411e-8b21-58620d68de7b@arm.com>
Date: Thu, 20 Feb 2025 11:05:57 +0000
From: Christian Loehle <christian.loehle@....com>
To: Oleksij Rempel <o.rempel@...gutronix.de>,
 Ulf Hansson <ulf.hansson@...aro.org>
Cc: kernel@...gutronix.de, linux-kernel@...r.kernel.org,
 linux-mmc@...r.kernel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Mark Brown <broonie@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>,
 Søren Andersen <san@...v.dk>
Subject: Re: [PATCH v2 3/6] mmc: core: refactor _mmc_suspend() for
 undervoltage handling

On 2/20/25 07:44, Oleksij Rempel wrote:
> Introduce an is_undervoltage parameter to _mmc_suspend() to apply a
> short power-off sequence and optionally flush the cache. This refactoring
> prepares for undervoltage support in a follow-up patch.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
>  drivers/mmc/core/mmc.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 6a23be214543..86b608843232 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -2104,20 +2104,27 @@ static int _mmc_flush_cache(struct mmc_host *host)
>  	return err;
>  }
>  
> -static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
> +static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
> +			bool is_undervoltage)

I see, sorry about missing this on 4/6 :/

>  {
> +	unsigned int notify_type;
>  	int err = 0;
> -	unsigned int notify_type = is_suspend ? EXT_CSD_POWER_OFF_SHORT :
> -					EXT_CSD_POWER_OFF_LONG;
> +
> +	if (is_undervoltage || is_suspend)
> +		notify_type = EXT_CSD_POWER_OFF_SHORT;
> +	else
> +		notify_type = EXT_CSD_POWER_OFF_LONG;
>  
>  	mmc_claim_host(host);
>  
>  	if (mmc_card_suspended(host->card))
>  		goto out;
>  
> -	err = _mmc_flush_cache(host);
> -	if (err)
> -		goto out;
> +	if (is_undervoltage) {
> +		err = _mmc_flush_cache(host);
> +		if (err)
> +			goto out;
> +	}

This is supposed to be !is_undervoltage, isn't it?

>  
>  	if (mmc_can_poweroff_notify(host->card) &&
>  	    ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend ||
> @@ -2144,7 +2151,7 @@ static int mmc_suspend(struct mmc_host *host)
>  {
>  	int err;
>  
> -	err = _mmc_suspend(host, true);
> +	err = _mmc_suspend(host, true, false);
>  	if (!err) {
>  		pm_runtime_disable(&host->card->dev);
>  		pm_runtime_set_suspended(&host->card->dev);
> @@ -2191,7 +2198,7 @@ static int mmc_shutdown(struct mmc_host *host)
>  		err = _mmc_resume(host);
>  
>  	if (!err)
> -		err = _mmc_suspend(host, false);
> +		err = _mmc_suspend(host, false, false);
>  
>  	return err;
>  }
> @@ -2215,7 +2222,7 @@ static int mmc_runtime_suspend(struct mmc_host *host)
>  	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
>  		return 0;
>  
> -	err = _mmc_suspend(host, true);
> +	err = _mmc_suspend(host, true, false);
>  	if (err)
>  		pr_err("%s: error %d doing aggressive suspend\n",
>  			mmc_hostname(host), err);